1. Field of the Invention
The present invention relates to a structure of a busbar unit which supplies current to an armature of a motor.
2. Description of the Related Art
An armature of a brushless motor includes a core back portion, a plurality of teeth radially extending from the core back portion, and coil windings formed by winding a conductive wire around each tooth. A rotor of the brushless motor is rotated when a driving current is supplied to the coil windings. A busbar unit for supplying the current from a power supply to the respective coil winding is provided in a housing of the brushless motor.
The busbar unit includes a plurality of busbars to which wiring from the power supply, and ends of the conductive wires forming the coil windings, are connected. With this configuration, the coil windings of the armature and the power supply are electrically connected to each other.
In general, the busbar unit is circular in plan view and has surfaces on both sides. The busbar unit is arranged coaxially with the armature so that they are axially opposed to each other. The busbar unit is connected at wire connector portions thereof to the conductive wires forming the coil windings.
In an exemplary known busbar unit, a number of busbars are arranged annularly and a plurality of wire connector portions extend therefrom. The wire connector portions are arranged on one of the surfaces of the busbar unit.
In another exemplary known busbar unit, a plurality of grooves are provided on one of the surfaces and busbars are arranged in the grooves. Each groove has a communication hole which runs through the busbar unit to the other surface. A portion of each busbar projects through the communication hole from the other surface. This projecting portion forms a wire connector portion.
As described above, it is necessary to connect ends of the conductive wires forming the coil windings to the wire connector portions in the busbar unit. This connection work is usually done manually.
In the aforementioned known busbar units, however, the wire connector portions are arranged on only one of the surfaces of the busbar unit. Thus, a distance between adjacent wire connector portions is too small to respectively connect the conductive wires to the wire connector portions. Especially in a motor having many slots, the number of coil windings is large because the number of coil windings corresponds to the number of slots. Therefore, the distance between the adjacent wire connector portions is very small, making the connection work difficult.